Microbe Hunters/Chapter 7

Microbe hunting has always been a queer humpty-dumpty business.

A janitor with no proper education was the first man to see microbes; a chemist put them on the map and made people properly afraid of them; a country doctor turned the hunting of them into something that came near to being a science; to save the lives of babies from the poison of one of the deadliest of them, a Frenchman and a German had to pile up mountains of butchered guinea-pigs and rabbits. Microbe hunting is a story of amazing stupidities, fine intuitions, insane paradoxes. If that is the history of the hunting of microbes, it is the same with the story of the science, still in its babyhood, of why we are immune to microbes. For Metchnikoff, the always excited searcher who in a manner of speaking founded that science—this Metchnikoff was not a sober scientific investigator; he was more like some hysterical character out of one of Dostoevski’s novels.

Élie Metchnikoff was a Jew, and was born in southern Russia in 1845, and before he was twenty years old, he said: “I have zeal and ability, I am naturally talented—I am ambitious to become a distinguished investigator!”

He went to the University of Kharkoff, borrowed the then rare microscope from one of his professors, and after peering (more or less dimly) through it, this ambitious young man sat himself down and wrote long scientific papers before he had ​any idea at all of what science was. He bolted his classes for months on end, not to play, but to read; not to read novels mind you but to wallow through learned works on the "Crystals of Proteic Substances" and to become passionate about inflammatory pamphlets whose discovery by the police would have sent him to the mines in Siberia. He sat up nights, drinking gallons of tea and haranguing his young colleagues (all of them forefathers of the present Bolsheviki) on atheism until they nicknamed him "God-Is-Not." Then, a few days before the end of the term, he crammed up the neglected lessons of months; and his prodigious memory, which was more like some weird phonograph record than any human brain, made it possible for him to write home to his folks that he had passed first and got a gold medal.

Metchnikoff was always trying to get ahead of himself. He sent papers to scientific journals while he was still in his teens; he wrote these papers frantically a few hours after he had trained his microscope on some bug or beetle; the next day he would look at them again, and find that what he had been so certain of, was not quite the same now. Hastily he wrote to the editor of the scientific journal: "Please do not publish the manuscript I sent you yesterday. I find I have made a mistake." At other times he was furious because his enthusiastic discoveries were turned down by the editors. "The world does not appreciate me!" he cried, and he went to his room, ready to die, dolefully whistling: "Were I small as a snail, I would hide myself in my shell."

But if Metchnikoff sobbed because his vivid talents were underestimated by his professors, he was also irrepressible. He forgot his contemplated suicides and his violent headaches in his incessant interest in all living things, but he was constantly spoiling his chances to do a good steady piece of scientific work by getting into quarrels with his teachers. Finally he told his mother (who had always spoiled him and believed in him): "I am especially interested in the study of protoplasm . . . but there is no science in Russia," so he rushed ​off to the University of Würzburg in Germany, only to find that he had arrived there six weeks ahead of the opening of school. He sought out some Russian students there, but they gave him the cold shoulder—he was a Jew—then, tired of life, he started back home, thinking of killing himself but with a few books in his satchel—and one of these was the just-published "Origin of Species" of Darwin. He read it, he swallowed the Theory of Organic Evolution with one great mental gulp, he became a bigoted supporter of it—from then on evolution was his religion until he began founding new scientific religions of his own.

He forgot his plans for suicide; he planned strange evolutionary researches; he lay awake nights, seeing visions—huge panoramas they were, of all beasts from cockroaches to elephants, as the children of some one remote and infinitely tiny ancestor. . . .

That conversion was Metchnikoff's real start in life, for now he set out (and kept at it for ten years), quarreling and expostulating his way from one laboratory to another, from Russia through Germany to Italy, and from Italy to the island of Heligoland. He worked at the evolution of worms. He accused the distinguished German zoölogist Leuckart of stealing his stuff; incurably clumsy with his fingers, he clawed desperately into a lizard to find the story of evolution its insides might tell him—and when he could not find what he wanted, he threw what was left of the reptile across the laboratory. Unlike Koch or Leeuwenhoek, who were great because they knew how to ask questions of nature, Metchnikoff read books on Evolution, was inspired, shouted "Yes!" and then by vast sloppy experiments proceeded to try to force his beliefs down nature's throat. Strange to say, sometimes he was right, importantly right as you will see. Up till now (it was in the late eighteen seventies) he knew nothing about microbes, but all the time his mania to prove the survival of the fittest was driving him toward his fantastic theory—partly true—of how mankind resists the assaults of germs.

​Metchnikoff's first thirty-five years were a hubbub and a perilously near disastrous groping toward this event—toward that great notoriety that waited for him on the Island of Sicily in the Mediterranean Sea. At twenty-three he had married Ludmilla Feodorovitch, who was a consumptive and had to be carried to the wedding in an invalid's chair. Then followed a pitiful four years for them. They dragged about Europe, looking for a cure; Metchnikoff trying in odd moments snatched from an irritatedly tender nursing of his wife, to do experiments on the development of green flies and sponges and worms and scorpions—trying above all to make some sensational discovery which might land him a well-paid professorship. "The survivors are not the best but the most cunning," he whispered, as he published his scientific papers and pulled his wires. . . .

Finally Ludmilla died; she had spent her last days solaced by morphine, and now Metchnikoff, who had caught the habit from her, wandered from her grave through Spain to Geneva, taking larger and larger doses of the drug—meanwhile, his eyes hurt him terribly, and what is a naturalist, a searcher, without eyes?

"Why live?" he cried, and took a dose of morphine that he knew must kill him, but the dose was too large, he became nauseated and threw it up. "Why live?" he cried again and took a hot bath and rushed out in the open air right afterwards to try to catch his death of pneumonia. But it seems that the wise witty gods who fashion searchers had other purposes for him. That very night he stopped, agape at the spectacle of a cloud of insects swirling round the flame of a lantern. "These insects live only a few hours!" he cried to himself. "How can the theory of the survival of the fittest be applied to them?" So he plunged back into his experiments.

Metchnikoff's grief was terrific but it did not last long. He was appointed Professor at the University of Odessa, and there he taught the Survival of the Fittest and became respected for his learning, and grew in dignity, and in less than ​two years after the death of Ludmilla, he had met Olga, a bright girl of fifteen, the daughter of a man of property. "His appearance is not unlike that of the Christ—he is so pale and seems so sad," whispered Olga. Soon after they were married.

From then on Metchnikoff's life was much less disastrous; he tried far less often to commit suicide; his hands began to catch up with his precocious brain—he was learning to do experiments. Never was there a man who tried more sincerely to apply his religion (which was science) to every part of his life. He took Olga in hand and taught her science and art, and even the art and science of marriage! She worshiped the profound certainties that science gave him, but said, long afterwards: "The scientific methods which Metchnikoff applied to everything might have been a grave mistake at this delicate psychological moment. . . ."

It was in 1883, when the discoveries of Pasteur and Koch had made everybody mad about microbes, that Metchnikoff turned suddenly from a naturalist into a microbe hunter. He had wrangled with the authorities of the University of Odessa, and departed for the Island of Sicily with Olga and her crowd of little brothers and sisters, and here he set up his amateur laboratory in the parlor of their cottage looking across the magic water to the blue Calabrian shore. His intuition told him that microbes were now the thing in science and he dreamed about making great discoveries of new microbes—he was sincerely interested in them as well, but he knew nothing about the subtle ways of hunting them, indeed he had hardly seen a germ. He stamped about his parlor-laboratory, expounding biological theories to Olga, studying starfish and sponges, telling the children fairy stories, doing everything in short that was as far as possible removed from those thrilling researches of Koch and Pasteur. . . .

​Then, one day, he began to study the way sponges and starfishes digest their food. Long before he had spied out strange cells inside these beasts, cells that were a part of their bodies, but cells that were free-lances, as it were, moving from place to place through the carcasses of which they formed a part, sticking out one part of themselves and dragging the rest of themselves after the part they had stuck out. Such were the wandering cells, which moved by flowing, exactly like that small animal, the ameba.

Metchnikoff sat down before his parlor table, and with that impatient clumsiness of a man whose hands seem unable to obey his brain, he got some little particles of carmine into the insides of the larva of a starfish. This was an ingenious and very original trick of Metchnikoff's, because these larvæ are as transparent as a good glass window; so he could see, through his lens, what went on inside the beast; and with excited delight he watched the crawling, flowing free-lance cells in this starfish ooze toward his carmine particles—and eat them up! Metchnikoff still imagined he was studying the digestion of his starfish, but strange thoughts—that had nothing to do with such a commonplace thing as digestion—little fog-wraiths of new ideas began to flutter through his head. . . .

The next day Olga took the children to the circus to see some extraordinary performing monkeys. Metchnikoff sat alone in his parlor, tugging at his biblical beard, gazing without seeing them at his bowls of starfish. Then—it was like that blinding light that bowled Paul over on his way to Damascus—in one moment, in the most fantastical, you would say impossible flash of a second, Metchnikoff changed his whole career.

"These wandering cells in the body of the larva of a starfish, these cells eat food, they gobble up carmine granules— but they must eat up microbes too! Of course—the wandering cells are what protect the starfish from microbes! Our wandering cells, the white cells of our blood—they must be what protects us from invading germs . . . they are the cause of ​immunity to diseases . . . they are what keep the human race from being killed off by malignant bacilli!"

Without one single bit of evidence, without any research at all, Metchnikoff jumped from the digestions of starfish to the ills of men. . . .

"I suddenly became a pathologist," he wrote in his diary (and this was not much more strange than if a cornet player should suddenly announce himself an astrophysicist!) ". . . Feeling that there was in this idea something of surpassing interest, I became so excited that I began striding up and down the room, and even went to the seashore to collect my thoughts."

Now Koch, precise microbe hunter that he was, would hardly have trusted Metchnikoff with the wiping of his microscope, but his ignorance of germs was nothing to this wild Russian.

"I said to myself that, if my theory was true, a sliver put into the body of a starfish larva . . . should soon be surrounded by wandering cells. . . ." And he remembered that when men run splinters into their fingers, and neglect to pull them out, those splinters are soon surrounded by pus—which consists largely of the wandering white cells of the blood. He rushed out into the garden back of the cottage, pulled some rose thorns off a little shrub which he had decorated as a Christmas tree for Olga's brother and sisters; he dashed back into his absurd laboratory and stuck these thorns into the body of one of his water-clear young starfish. . . .

Up he got, at dawn the next morning, full of wild hopes,—and he found his guess had come true. Around the rose-slivers in the starfish were sluggish crawling masses of its wandering cells! Nothing more was necessary (such a jumper at conclusions was he) to stamp into his brain the fixed idea that he now had the explanation of all immunity to diseases; he rushed out that morning to tell famous European professors, who happened then to be in Messina, all about his great idea. "Here is why animals can withstand the attacks of microbes," he said, and he talked with such enthusiastic eloquence about how ​the wandering cells of the starfish tried to eat the rose thorns (and he could show it so prettily too) that even the most eminent and pope-like Professor Doctor Virchow (who had sniffed at Koch) believed him!

Metchnikoff was now a microbe hunter. . . .

With Olga and the children flapping along and keeping up as best they could, Metchnikoff hurried to Vienna to proclaim his theory that we are immune to germs because our bodies have wandering cells to gobble germs up; he made a bee-line for the laboratory of his friend, Professor Claus—who was a zoölogist, and knew nothing about microbes either, and so was properly amazed:

"I would be greatly honored to have you publish your theory in my Journal," said Claus.

"But I must have a scientific name for these cells that devour microbes—a Greek name—what would be a Greek name for such cells?" cried Metchnikoff.

Claus and his learned colleagues scratched their heads and peered into their dictionaries and at last they told him: "Phagocytes! Phagocyte is Greek for devouring cell—phagocytes is what you must call them!"

Metchnikoff thanked them, tacked the word "phagocyte" to the head of his mast, and set sail on the seas of his exciting career as a microbe hunter with that word as a religion, an explanation of everything, a slogan, a means of gaining a living—and, though you may not believe it, that word did result in something of a start at finding out how it is we are immune! From then on he preached phagocytes, he defended their reputations, he did some real research on them, he made enemies about them, he doubtless helped to start the war of 1914 with them, by the bad feeling they caused between France and Germany.

He went from Vienna to Odessa, and there he gave a great ​scientific speech on "The Curative Forces of the Organism" to the astonished doctors of the town. His delivery was superb; his sincerity was undoubted—but there is no record of whether or not he told the amazed doctors that he had not, up till then, so much as seen one phagocyte gobble up a single malignant microbe. Everybody—and this includes learned doctors—will stop to watch a dog fight; so this idea of Metchnikoff's, this story of our little white blood cells rushing to an endless series of Thermopylæs to man the pass against murderous germs—this yarn excited them, convinced them. . . .

But Metchnikoff knew he would have to have real evidence, and presently he found it, beautifully clear, in water fleas. For a time he forgot speeches and began fishing water fleas out of ponds and aquariums; here he was deucedly ingenious again, for these small animals, like starfish larvæ, were transparent so that he could see through his lens what went on inside them. For once he grew patient, and searched, like the real searcher that he so rarely was, for some disease that a water flea perchance might have. This history has already made it clear that microbe hunters usually find other things than they set out to look for—but Metchnikoff just now had different luck; he watched his water fleas in their aimless daily life, and suddenly, through his lens he saw one of these beasts swallow the sharp, needle-like spores of a dangerous yeast. Down into the wee gullet went these needles, through the walls of the flea's stomach they poked their sharp points, and into the tiny beast's body they glided. Then—how could the gods favor such a wild man so!—Metchnikoff saw the wandering cells of the water flea, the phagocytes of this creature, flow towards those perilous needles, surround them, eat them, melt them up, digest them. . . .

When—and this happened often too and so made his theory perfect—the phagocytes failed to go out to battle against the deadly yeast needles, these invaders budded rapidly into swarming yeasts, which in their turn ate the water flea, poisoned him—and that meant good-by to him!

​Here Metchnikoff had peeped prettily into a thrilling, deadly struggle on a tiny scale, he had spied upon the up till now completely mysterious way in which certain living creatures defend themselves against their would-be assassins. His observations were true as steel, and you will have to grant they were devilishly ingenious, for who would have thought to look for the why of immunity in such an absurd beast as the water flea? Now Metchnikoff needed nothing more to convince him of the absolute and final rightness of his theory, he probed no deeper into this struggle (which Koch would have spent years over) but wrote a learned paper:

"The immunity of the water flea, due to the help of its phagocytes, is an example of natural immunity . . . for, once the wandering cells have not swallowed the yeast spore at the moment of its penetration into the body, the yeast germinates . . . secretes a poison which drives the phagocytes back not only, but kills them by dissolving them completely."

Then Metchnikoff went to see if this same battle took place in frogs and rabbits, and suddenly, in 1886, the Russian people were thrilled by Pasteur's saving of sixteen of their folk from the bite of the mad wolf. The good people of Odessa and the farmers of the Zemstvo round about gave thanks to God, hurrahs for Pasteur, and a mighty purse of roubles for a laboratory to be started at once in Odessa. And Metchnikoff was appointed Scientific Director of the new Institute—for had not this man (they forgot for a moment he was Jewish) studied in all the Universities of Europe, and had he not lectured learnedly to the doctors of Odessa, telling about the phagocytes of the blood, which gobble microbes?

"Who knows?" you can hear the people saying. "Maybe in our new Institute, Professor Metchnikoff can train these little phagocytes to gobble up all microbes?"

Metchnikoff accepted the position, but told the authorities, ​shrewdly: "I am only a theoretician; I am overwhelmed with researches—some one else will have to be trained to make vaccines, to do the practical work."

Nobody in Odessa knew anything about microbe hunting then, so Metchnikoff's friend, Doctor Gamaléia, was sent to the Pasteur Institute in Paris posthaste. The citizens were anxious to begin to be prevented from having diseases; they bawled for vaccines. So Gamaléia, after a little while in Paris, where he watched Roux and Pasteur and learned a great deal from them, but not quite enough—this Gamaléia came back and started to make anthrax vaccines for the sheep of the Zemstvo, and rabies vaccines for the people of the town. "All should now go very well!" cried Metchnikoff (he knew nothing of the nasty tricks virulent microbes can play) and he retired to his theoretical fastnesses to grapple with rabbits and dogs and monkeys, to see if their phagocytes would swallow the microbes of consumption and relapsing fever and erysipelas. Scientific papers vomited from his laboratory, and the searchers of Europe began to be excited by the discoveries of this strange genius in the south of Russia. But he began to have troubles with his theory, for dogs and rabbits and monkeys—alas—are not transparent, like water fleas. . . .

Then the shambles began. Gamaléia and the other members of Metchnikoff's practical staff began to fight among themselves and mix up vaccines; microbes spilled out of tubes; the doctors of the town—naturally a little jealous of this new form of healing—started to snoop into the laboratory, to ask embarrassing questions, to start whispers going through the town: "Who is this Professor Metchnikoff—he hasn't even a doctor's certificate. He is only a naturalist, a mere bug-hunter—how can he know anything about preventing diseases?"

"Where are those cures?" demanded the people. "Give us our preventions!" shouted the farmers—who had gone down into their socks for good roubles. Metchnikoff came out of the fog of his theory of phagocytes for a moment, and tried to satisfy them by sowing chicken cholera bacilli among the ​meadow mice which were eating up the crops. But, alas, a lying, inflammatory report appeared in the daily paper, screaming that this Metchnikoff was sowing death—that chicken cholera could change into human cholera. . . .

"I am overwhelmed with my researches," muttered Metchnikoff. "I am a theoretician—my researches need a peaceful shelter in which to be developed. . . ." So he asked for a vacation, got it, packed his bag, and went to the Congress of Vienna to tell everybody about phagocytes, and to look for a quiet place in which to work. He must get away from that dreadful need to prove that his theories were true by dishing out cures to impatient authorities and peasants who insisted on getting their money's worth out of research. From Vienna he went to Paris to the Pasteur Institute, and there a great triumph and surprise waited for him. He was introduced to Pasteur, and at once Metchnikoff exploded into tremendous explanations of his theory of phagocytes. He made a veritable movie of the battle between the wandering cells and microbes. . . .

The old captain of the microbe hunters looked at Metchnikoff out of tired gray eyes that now and then sparkled a little: "I at once placed myself on your side, Professor Metchnikoff," said Pasteur, "for I have been struck by the struggle between the divers microörganisms which I have had occasion to observe. I believe you are on the right road."

Although the struggles Pasteur mentioned had nothing to do with phagocytes gobbling up microbes, Metchnikoff—and this is not unnatural—was filled with a proud joy. The greatest of all microbe hunters really understood him, believed in him. . . . Olga's father had died, leaving them a modest income, here in Paris his theory of phagocytes would have the prestige of a great Institute back of it. "Is there a place for me here?" he asked. "I wish only to work in one of your laboratories in an honorary capacity," begged Metchnikoff.

Pasteur knew how important it was to keep the plain people thrilled about microbe hunting—it is the drama of science that ​they can understand—so Pasteur said: "You may not only come to work in our laboratory, but you shall have an entire laboratory to yourself!" Metchnikoff went back to Odessa, getting a dreadful snubbing from Koch on the way, and wondered whether it would not be best to give up his tidy salary at the Russian Institute, to get away from these people yelling for results. . . . But he began to take up his work again, when suddenly something happened that left no doubt in his mind as to what he had better do.

In response to the farmer's complaints of "Where are your vaccines, our flocks are perishing from anthrax!" Metchnikoff had told Dr. Gamaléia to start giving sheep the anthrax vaccine on a large scale. Then, one bright morning, while the Director was with Olga in their summer home, in the country, a fearful telegram came to him from Gamaléia:

"MANY THOUSANDS OF SHEEP KILLED BY THE ANTHRAX VACCINE."

A few months later they were safely installed in the new Pasteur Institute in Paris, and Olga (who enjoyed painting and sculpture much better—but who would do anything for her husband because he was a genius, and always kind to her) this good wife, Olga, held his animals and washed his bottles for Metchnikoff. From then on they marched, hand in hand, over a road strewn with their picturesque mistakes, from one triumph to always greater victories and notorieties.

Metchnikoff bounced into the austere Pasteur Institute and started a circus there which lasted for twenty years; it was as if a skilled proprietor of a medicine show had become pastor of a congregation of sober Quakers. He came to Paris and found himself already notorious. His theory of immunity—it would be better to call it an exciting romance, rather than a ​theory—this story that we are immune because of a kind of battle royal between our phagocytes and marauding microbes, this yarn had thrown the searchers of Europe into an uproar. The microbe hunters of Germany and Austria for the most part did not believe it—on the contrary, tempted to believe it by its simplicity and prettiness, they denied it with a peculiar violence. They denounced Metchnikoff in congresses and by experiments. One old German, Baumgarten, wrote a general denunciation of phagocytes, on principle, once a year, in an important scientific journal. For a little while Metchnikoff wavered; he nearly swooned, he couldn't sleep nights, he thought of going back to his soothing morphine; he even contemplated suicide once more—oh! why could not those nasty Germans see that he was right about phagocytes? Then he recovered. Something seemed to snap in his brain, he became courageous as a lion, he started a battle for his theory—it was a grotesque, partly scientific wrangle—but, in spite of all its silliness, it was an argument that laid the foundations of the little that is known to-day about why we are immune to microbes.

"I have demonstrated that the serum of rats kills anthrax germs—it is the blood of animals not their phagocytes. that makes them immune to microbes," shouted Emil Behring, and all the bitter enemies of Metchnikoff sang Aye in the chorus. The scientific papers published to show that blood is the one important thing would fill three university libraries.

"It is the phagocytes that eat up germs and so defend us," roared Metchnikoff in reply. And he published ingenious experiments which proved anthrax bacilli grow exuberantly in the blood of sheep which have been made immune by Pasteur's vaccine.

Neither side would budge from this extreme, prejudiced position. For twenty years both sides were so enraged they could not stop to think that perhaps both our blood and our phagocytes might work together to guard us from germs. That ​fight was a kind of magnificent but undignified shouting of "You're a liar— On the contrary, it's you that's the liar!" which blinded Metchnikoff and his opponents to the idea that it might be neither the blood nor the phagocytes which are at the bottom of our resistance to some diseases. If they had only stopped for a moment, wiped their brows and cleaned the blood from their mental noses, to remember how little they knew, how slowly they should go—considering what subtle complicated stuff this blood and those phagocytes are—if they had only remembered how foolish, in the darkness of their ignorance, it was to cook up any explanation at all of why we are immune! If Metchnikoff had only kept on, obscure in Odessa, with his beautiful researches on the why of the wandering cells of the water fleas eating up those terrible little yeasts. . . . If he had only been patient and tried to get to the bottom of that!

But the stumbling strides of microbe hunters are not made by any perfect logic, and that is the reason I may write a grotesque, but not perfect story of their deeds.

In the grand days of Pasteur's fight with anthrax and his victory against rabies, he had worked like some subterranean distiller of secret poisons, with only Roux and Chamberland and one or two others to help him. In that dingy laboratory in the Rue d'Ulm he had been very impolite, even nasty, to all curious intruders and ambitious persons. He even chased adoring pretty ladies away. But Metchnikoff!

Here was an entirely different sort of searcher. Metchnikoff had an immensely impressive beard and a broad forehead that crowned eyes which squinted vividly—and intelligently—from behind his spectacles. His hair grew down over the back of his neck in a way that showed you he was too deep in thoughts to think of having it cut. He knew everything! He could tell—and it was authentic—of countless biological mysteries; he had seen the wandering cells of a tadpole turn it into a frog by eating the tadpole's tail, and he had built circles of fire around scorpions to show that these unhappy creatures, failing ​to find a way out, do not commit suicide by stinging themselves to death. He told these horrors in a way to make you feel the remorseless flowing and swallowing of the wandering cells—you could hear the hissing of the doomed and baffled scorpion. . . .

He had brilliant ideas for experiments and was always trying to carry out these ideas—intensely—but at any moment he was ready to drop his science to praise the operas of Mozart or whistle the symphonies of Beethoven, and sometimes he seemed to be more learned about the dramas and the loves of Goethe than about those phagocytes upon which his whole fame rested. He refused to wear a high hat toward lesser men; he would see any one and was ready to believe anything—he even tried the remedies of patent medicine quacks on dying guinea-pigs. And he was a kind man. When his friends were sick he overwhelmed them with delicacies and advice and shed sincere tears on their pillows—so that finally they nicknamed him "Mamma Metchnikoff." His views on the intimate instincts and necessities of life were astoundingly unlike those of any searcher I have ever heard of. "The truth is that artistic genius and perhaps all kinds of genius are closely associated with sexual activity . . . so, for example, an orator speaks better in the presence of a woman to whom he is devoted."

He insisted that he could experiment best when pretty girls were close by!

Metchnikoff's workshop in the Pasteur Institute was more than a mere laboratory; it was a studio, it had the variegated attractions of a country fair; it radiated the verve and gusto of a three-ringed circus. Is it any wonder, then, that young doctors, eager to learn to hunt microbes, flocked to him from all over Europe? Their brains responded to this great searcher who was also a hypnotist, and their fingers flew to perform the ten thousand experiments, ideas for which belched out of the mind of Metchnikoff like an incessant eruption of fireworks.

"Mr. Saltykoff!" he would cry. "This student of Professor ​Pfeiffer in Germany claims that the serum of a guinea-pig will keep other guinea-pigs from dying of hog-cholera. Will you be so good as to perform an experiment to see if that is so?" And the worshiping Saltykoff rushed off—knowing what the master wanted to prove—to show that the German claims were nonsense. For a hundred other intricate tests, for which his own fingers were too impatient, Metchnikoff called upon Blagovestchensky, or Hugenschmidt, or Wagner, or Gheorgiewski, or the now almost forgotten Sawtchenko. Or when these were all busy, then there was Olga to be lured away from her paints and clay models—Olga could be depended upon to prove the most delicate points. In that laboratory there were a hundred hearts that beat as one and a hundred minds with but a single thought—to write the epic of those tiny, roundish, colorless, wandering cells of our blood, those cells, which, smelling from afar the approach of a murderous microbe, swam up the current of the blood, crawled strangely through the walls of the blood vessels to do battle with the germs and so guard us from death.

The great medical congresses of those brave days were exciting debating societies about microbes, about immunity, and it was in the weeks before a congress (Metchnikoff always went to them) that his laboratory buzzed with an infernal rushing to and fro. "We must hurry," Metchnikoff exclaimed, "to make all of the experiments necessary to support my arguments!" The crowd of adoring assistants then slept two hours less each night; Metchnikoff rolled up his sleeves, too, and seized a syringe. Young rhinoceros beetles, green frogs, alligators, or weird Mexican axolotls were brought from the animal house by the sweating helpers (sometimes the ponds were dredged for perch and gudgeon). Then the mad philosopher, his eyes alight, his broad face so red that it glowed like some smoldering brush-fire under his beard, his mustaches full of bacilli spattered into it by his excited and poetic gestures—this Metchnikoff, I say, proceeded to inject swarms of microbes into one or another of his uncomplaining, cold-blooded me​nagerie. "I multiply experiments to support my theory of phagocytes!" he was wont to say.

It is amazing, when you remember that his brain was always inventing stories about nature, how often these stories turned out to be true when they were put to the test of experiment. A German hunter had claimed: "There is nothing to Metchnikoff's theory of phagocytes. Everybody knows that you can see microbes inside of phagocytes—they have undoubtedly been gobbled up by the phagocytes. But these wandering cells are not defenders, they are mere scavengers—they will only swallow dead microbes!" The London Congress of 1891 was drawing near; Metchnikoff shouted for some guinea-pigs, vaccinated them with some cholera-like bacilli that his old friend, the unfortunate Gamaléia, had discovered. Then, a week or so later, the big-bearded philosopher shot some of these living, dangerous bacilli into the bellies of vaccinated beasts. Every few minutes, during the next hours, he ran slender glass tubes into their abdomens, sucked out a few drops of the fluid there, and put it before the more or less dirty lens of his microscope, to see whether the phagocytes of the immune beasts were eating up Gamaléia's bacilli. Presto! These roundish crawling cells were crammed full of the microbes!

"Now I shall prove that these microbes inside the phagocytes are still alive!" cried Metchnikoff. He killed the guinea-pig, slashed it open, and sucked into another little glass tube some of the grayish slime of wandering cells which had gathered in the creature's belly to make meals off the microbes. In a little while—for they are very delicate when you try to keep them alive outside the body—the phagocytes had died, burst open, and the live bacilli they had swallowed galloped out of them! Promptly, when Metchnikoff injected them, these mi​crobes that had been swallowed, murdered guinea-pigs who were not immune.

By dozens of brilliant experiments of this kind, Metchnikoff forced his opponents to admit that phagocytes, sometimes, can eat vicious microbes. But the pitiful waste of this brainy Metchnikoff's life was that he was always doing experiments to defend an idea, and not to find the hidden truths of nature. His experiments were weird, they were often fantastically entertaining, but they were so artificial—they were so far away from the point of what it is that makes us immune. You would think that his brain, which seemed to be able to hold all knowledge, would have dreamed of subtle tests to find out just how it is that one child can be exposed to consumption and never get it, while some carefully and hygienically raised young girl dies from consumption at twenty. There is the riddle of immunity (and it is still completely a riddle!). "Oh! it is doubtless due to the fact that her phagocytes are not working!" Metchnikoff would have exclaimed, and then he might rush off to flabbergast some opponent by proving that the phagocytes of an alligator eat up typhoid fever bacilli—which never bother alligators anyway.

The devotion of the workers in his laboratory was amazing. They let him feed them virulent cholera bacilli (even one of those pretty inspirational girls swallowed them!) to prove that the blood has nothing to do with our immunity to cholera. For years—he himself said that it was an insanity of his—he was fond of toying with the lives of his researching slaves, and the only thing that excused him was his perfect readiness to risk death along with them. He swallowed more tubes of cholera bacilli than any of them. In the midst of this dangerous business, one of the assistants, Jupille, became violently sick with real Asiatic cholera and Metchnikoff's remorse was immoderate. "I shall never survive the death of Jupille!" he moaned, and Olga, that good wife, had to be on her guard day and night to keep her famous husband from one of his ​(always fruitless) attempts at suicide. At the end of these strange experiments, Metchnikoff jabbed needles into the arms of the survivors, drew blood from them, and triumphantly found that this blood did not protect guinea-pigs from doses of virulent cholera germs. How he hated the idea of blood having any importance! "Human cholera gives us another example," he wrote, "of a malady whose cure cannot be explained by the preventive properties of the blood."

When some more than ordinarily independent student would come whispering to him that he had discovered a remarkable something about blood, Metchnikoff became magnificent like Moses coming down off Mt. Sinai—searchers for mere truth had a bad time in that laboratory, and you can imagine the great dauntless champion of phagocytes ordering a dissenter from his theory to be burned, and then weeping inconsolably over him afterwards. But, just the same, Metchnikoff—so great was the number of experiments made by an always changing crowd of eager experimenters in his laboratory—this Metchnikoff was partly responsible for the discovery of some of the most astounding virtues of blood. For, in the midst of his triumphs, Jules Bordet came to work with the master. This Bordet was the son of the schoolmaster of the village of Soignies in Belgium. He was timid, he seemed insignificant, he had careless ways and watery-blue, absent-minded eyes—eyes that saw things nobody else was looking for. Bordet set to work there, and right in the shadow of the master's beard, while the walls shook with the slogan "Phagocytes!"—the Belgian pried into the mystery of how blood kills germs; he laid the foundation for those astounding delicate tests which tell whether blood is human blood, in murder cases. It was here too, that Bordet began the work which led, years later, to the famous blood test for syphilis—the Wassermann reaction. Metchnikoff was often annoyed with Bordet, but he was proud of him too, and whenever Bordet found anything in blood that was harmful to microbes, and might help to make people immune to them, Metchnikoff consoled himself by in​venting more or less accurate experiments which showed that these microbe-killing things came from the phagocytes, after all. Bordet did not remain long in Metchnikoff's laboratory. . . .

Toward the end of the nineteenth century, when romantic microbe hunting began to turn into a regular profession, recruited from good steady law-abiding young doctors who were not prophets or reckless searchers—in those days Metchnikoff's bitter trials with people who didn't believe him began to be less terrible. He received medals and prizes of money, and even the Germans clapped their hands and were respectful when he walked majestically into some congress. A thousand searchers had spied phagocytes in the act of gobbling harmful germs—and although that did not explain at all why one man dies from an attack of pneumonia microbes, while another breaks into a sweat and gets better—just the same there is no doubt that pneumonia germs are sometimes eaten and so got rid of by phagocytes. So Metchnikoff, after you discount his amazing illogic, his intolerance, his bullheadedness, really did discover a fact which may make life easier for suffering mankind. Because, some day, a dreamer, an experimenting genius like the absent-minded Bordet may come along—and he may solve the riddle of why phagocytes sometimes gobble germs and sometimes do not—he might even teach phagocytes always to eat them. . . .

At last Metchnikoff began really to be happy. His opponents were partly convinced, and partly they stopped arguing with him because they found it was no use—he could always experiment more tirelessly than they, he could talk longer, he could expostulate more loudly. So Metchnikoff, at the beginning of the twentieth century, sat down to write a great book on all that he had found out about why we are immune. It was an enormous treatise you would think it would take ​a lifetime to write. It was written in a style Flaubert might have envied. He made every one of the ten thousand facts in it vivid, and every one of them was twisted prettily to prove his point. It is a strange novel with a myriad of heroes—the wandering cells, the phagocytes of all the animals of the earth.

His fame made him take a real delight in being alive. Twenty years before, detesting the human race, sorry for himself, and hating life, he had told Olga: "It is a crime to have children—no human being should consciously reproduce himself." But now that he had begun to take delight in existence, the children of Sèvres, the suburb where he lived, called him "Grandpa Christmas" as he patted their heads and gave them candy. "Life is good!" he told himself. But how to hang onto it, now that it was slipping away so fast? In only one way, of course—by science!

"Disease is only an episode!" he wrote. "It is not enough to cure (he had discovered no cures) . . . it is necessary to find out what the destiny of man is, and why he must grow old and die when his desire to live is strongest." Then Metchnikoff abandoned work on his dead phagocytes and set out to found fantastic sciences to explain man's destiny, and to avoid it. To one of these, the science of old age, he gave the sonorous name "Gerontology," and he gave the name "Thanatology" to the science of death. What awful sciences they were; the ideas were optimistic; the observations he made in them were so inaccurate that old Leeuwenhoek would have turned over in his grave had he known about them; the experiments Metchnikoff made, to support these sciences, would have caused Pasteur to foam with indignation that he had ever welcomed this outlandish Russian to his laboratory. And yet—and yet—the way really to prevent one of the most hideous microbic diseases came out of them. . . .

Metchnikoff dreaded the idea of dying but knew that he and everybody else would have to—so he set out to devise a hope (there was not one particle of science in this) for an easy death. Somewhere in his vast hungry readings, he had run across the ​report of two old ladies who had become so old that they felt no more desire for life—they wanted to die, just as all of us want to go to sleep at the end of a hard day’s work. "Ha!" cried Metchnikoff, "that shows that there is an instinct for death just as there is an instinct for sleep! The thing to do is to find a way to live long enough in good health until we shall really crave to die!"

Then he set out on a thorough search for more of such lucky old ladies, he visited old ladies' homes, he rushed about questioning old crones, with their teeth out, who were too deaf to hear him. He went all the way from Paris to Rouen to interview (on the strength of a newspaper rumor) a dame reported to be a hundred and six. But, alas, all of the oldsters he talked to were strong for life, he never found any one like the two legendary old ladies. Just the same he cried: "There is a death instinct!" Contrary facts never worried him.

He studied old age in animals; and people were always sending him gray-haired dogs and dilapidated ancient cats; he published a solemn research on why a superannuated parrot lived to be seventy. He owned an ancient he-turtle, who lived in his garden, and Metchnikoff was overjoyed when this venerable beast—at the great age of 86—mated with two lady turtles and became the father of broods of little turtles. He dreaded the passing of the delights of love, and exclaimed, remembering his turtle: "Senility is not so profoundly seated as we suppose!"

But to push back old age? What is at the bottom of it? A Scandinavian scientist, Edgren, had made a deep study of the hardening of the arteries—that was the cause of old age, suggested Edgren, and among the causes of the hardening of the arteries were the drinking of alcohol, syphilis, and certain other diseases.

"A man is as old as his arteries, that is true," muttered Metchnikoff, and he decided to study the riddle of how that loathsome disease hardens the arteries. It was in 1903. He had just received a prize of five thousand francs, and Roux— ​who, though so different, so much more the searcher, had always stuck by this wild Metchnikoff—Roux had got the grand Osiris prize of one hundred thousand francs. Never were there two men so different in their ways of doing science, but they were alike in caring little for money, and together they decided to use all of these francs—and thirty thousand more which Metchnikoff had wheedled out of some rich Russians—to study that venereal plague, to attempt to give it to apes, to try to discover its then mysterious virus, to prevent it, to cure it if possible. And Metchnikoff wanted to study how syphilis hardened the arteries.

So they bought apes with this money. French governors in the Congo sent black boys to scour the jungles for them, and presently large rooms at the Pasteur Institute were a-chatter with chimpanzees and orang-outangs, and the cries of these were drowned out by the shrieking of the sacred monkey of the Hindoos, and the caterwaulings of the comical little Macacus cynemolgus.

Almost at once Roux and Metchnikoff made an important find; their experiments were ingenious and they had about them a certain tautness and clearness that was strangely un-Metchnikoffian. Their laboratory began to be the haunt of unfortunate men who had just got syphilis; from one of these they inoculated an ape—and the very first experiment was a success. The chimpanzee developed the disease. From then on, for more than four years they toiled, transmitting the diseases from one ape to another, looking for the sneaking slender microbe but not finding it, trying to find ways to weaken the virus—as Pasteur had done with the unknown germ of rabies—in order to discover a preventive vaccine. Their monkeys died miserably of pneumonia and consumption, they got loose and ran away. While Metchnikoff, not too deftly, scratched the horrible virus into them, the apes bit him and scratched him back—and then Metchnikoff did a strange and clever experiment. He scratched a little syphilitic virus into the ear of an ape, and twenty-four hours later he cut ​off that ear! The ape never showed one sign of the disease in any other part of his body. . . .

"That means," cried Metchnikoff, "that the germ lingers for hours at the spot where it gets into the body—now, as in men we know exactly where the virus gets in, maybe we can kill it before it ever spreads—since in this disease we know just when it gets in, too!"

So Metchnikoff, with Roux always being careful and insisting upon good check experiments—so Metchnikoff, after all of his theorizing about why we are immune, performed one of the most profoundly practical of all the experiments of microbe hunting. He sat himself down and invented the famous calomel ointment—that now is chasing syphilis out of armies and navies the world over. He took two apes, inoculated them with the syphilitic virus fresh from a man, and then, one hour later, he rubbed the grayish ointment into that scratched spot on one of his apes. He watched the horrid signs of the disease appear on the unanointed beast, and saw all signs of the disease stay away from the one that had got the calomel.

Then for the last time Metchnikoff's strange insanity got hold of him. He forgot his vows and induced a young medical student, Maisonneuve, to volunteer to be scratched with syphilis from an infected man. Before a committee of the most distinguished medical men of France, this brave Maisonneuve stood up, and into six long scratches he watched the dangerous virus go. It was a more severe inoculation than any man would ever get in nature. The results of it might make him a thing for loathing, might send him, insane, to his death. . . . For one hour Maisonneuve waited, then Metchnikoff, full of confidence, rubbed the calomel ointment into the wounds—but not into those which had been made at the same time on a chimpanzee and a monkey. It was a superb success, for Maisonneuve showed never a sign of the ugly ulcer, while the simians, thirty days afterwards, developed the disease—there was no doubt about it.

Moralists—and there were many doctors among these, mind ​you—raised a great clamor against these experiments of Metchnikoff. "It will remove the penalty of immorality!" said they, "to spread abroad such an easy and a perfect means of prevention!" But Metchnikoff only answered: "It has been objected that the attempt to prevent the spread of this disease is immoral. But since all means of moral prophylaxis have not prevented the great spread of syphilis and the contamination of innocents, the immoral thing is to restrain any available means we have of combating this plague."

Meanwhile he was scheming and groping about and having dreams about other things that might cause the arteries to harden, and suddenly he invented another cause—surely no one can say he discovered it!—"auto-intoxication, poisoning from the wild, putrefying bacilli in our large intestines—that is surely a cause of the hardening of the arteries, that is what helps us to grow old too soon!" he cried. He devised chemical tests—what awful ones they were—that would show whether the body was being poisoned from the intestine. "We would live much longer," he said, "if we had no large intestine, indeed, two people are on record, who had their large intestine cut out, and live perfectly well without it." Strange to say, he did not advocate cutting the bowels out of every one, but he set about thinking up ways of making things there uncomfortable for the "wild bacilli."

His theory was a strange one, and caused laughter and jeers and he began to get into trouble again. People wrote in, reminding him that elephants had enormous large intestines but lived to be a hundred in spite of them; that the human race, in spite of its large intestine, was one of the longest-lived species on earth. He engaged in vast obscene arguments about why evolution has allowed animals to keep a large intestine—then suddenly he hit on his great remedy for auto-intoxication. There were villages in Bulgaria where people were alleged to ​live to be more than a hundred. Metchnikoff didn't go down there to see—he believed it. These ancient people lived principally upon sour milk, so went the story. "Ah! there's the explanation," he muttered. He put the youngsters in his laboratory to studying the microbe that made milk sour—and in a little while the notorious Bulgarian bacillus made its bow in the rank of patent medicines.

"This germ," explained Metchnikoff, "by making the acid of sour milk, will chase the wild poisonous bacilli out of the intestine." He began drinking huge draughts of sour milk himself, and later, for years, he fed himself cultivations of the Bulgarian bacillus. He wrote large books about his new theory and a serious English journal acclaimed them to be the most important scientific treatises since Darwin's "Origin of Species." The Bulgarian bacillus became a rage, companies were formed, and their directors grew rich off selling these silly bacilli. Metchnikoff let them use his name (though Olga insists he never made a franc from that) for the label.

For nearly twenty years Metchnikoff austerely lived to the letter of his new theory. He neither drank alcoholic drinks nor did he smoke. He permitted himself no debaucheries. He was examined incessantly by the most renowned specialists of the age. His rolls were sent to him in separate sterilized paper bags so that they would be free from the wild, auto-intoxicating bacilli. He constantly tested his various juices and excretions. In those years he got down untold gallons of sour milk and swallowed billions of the beneficent bacilli of Bulgaria. . . .

And he died at the age of seventy-one.